In welding applications the electrical power required is often produced by a generator. In the conventional welding generator, the welding current is controlled by controlling the excitation current, which is direct current fed into the field windings. This current can be produced from an external source, such as a separate generator on the shaft of the welding motor generator set, or from the dynamo of a combustion engine driving the welding generator.
In order to control the generated welding current, the excitation current must be correspondingly controlled. This necessitates the use of a voltage regulator which controls the excitation current in accordance with the welding current required. Such regulators vary in sophistication, but invariably add to the cost of the apparatus.
A further problem with such welding generators is that when the output of the stator is short circuited, and if there is no specific current limiting, the regulator will attempt to drive the set at maximum current. The output current can rise to unsafe levels, causing damage to the alternator. To overcome this problem extra safety circuitry is required.
This invention will describe, in use, a welding generator. The scope of invention is however not limited to this application.